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Hi all, I'm new to the C6711DSK and I'm hoping you guys can help me to sort out one or two problems I'm having. I'm attempting to use the EDMA controller to send and receive data via the McBSP which in turn interfaces to the AIC23EVM codec (which sends and receives 32bit samples (16bits per left and right channel)). Currently, I can send and receive data to the McBSP using the polling technique and this is working perfectly with no problems what so ever, so I'm now ready to advance to the EDMA stage. To do this, I thought I could make a few changes to the "audio" project example in the ccs examples folder, but I haven't been that lucky. This is how I've set things up - PIP (rxPipe and txPipe) - bufseg - SDRAM bufalign - 4 framesize in words - 64 num of frames - 2 EDMA TX - Frame Sync = None ESIZE = 32bit Source 2DS = Disabled SUM = Index Address = 0x00000000 Destination 2DS = Disabled DUM = None Address = DSS_hMcbsp0 (McBSP handle) Element Index = 2 Frame Index = 2 TCINT = Enable TCC = 12 FC=0 EC2 ECRLD=0 Link = Disabled PRI (low) and something similar for Rx - I have the receive priority set to high for receiving. These settings give me a sample rate which is half of that expected, for both receiving and transmitting. In other words, if I output a 100Hz wave, I get a 50Hz wave on my oscilloscope. I've tried changing every value I can think of - number of PIP frames, size of PIP frame, all the EDMA settings. I get all kinds of crazy outputs when I attempt this, but not the output I expect. Do I need to change my McBSP settings? If they work correctly for polling, then I presume there is nothing I have to change if I wish to use EDMA instead. To make sure that the sampling rate of the codec is not being changed, I placed a count in the EDMA IRS. When this count expires, I call EDMA_RSET(EER, 0x0000) and revert to polling for the samples. The output signal then doubles in frequency. This means that the codec is correctly configured for 88200Hz. It seems to me that two output samples are being outputted when only one should be. How might this be happening? Both left and right channels have the same outputs unless the upper or lower word of a sample is different. I tried changing the Element Index to one, and this is still the case, although the output with respect to time is muddled up. I've spent the last few days trying to decipher the "audio" project with limited success. Could anyone offer me a simpler example? Thanks for your help, Francis. |
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EDMA interface to McBSP
Started by ●November 29, 2003
Reply by ●January 11, 20042004-01-11
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Just to add to this thread: I m experiencing the same issue on EDMA c6416. while trying to implement the McBSP as a UART interface using EDMA as implemented in the application report SPRA633A. The same thing happen the EDMA interrupt is not occuring. Anyone who can help please reply. --- In , "rockall_rebel" <rockall_rebel@y...> wrote: > Hi all, > > I'm new to the C6711DSK and I'm hoping you guys can help me to sort > out one or two problems I'm having. > > I'm attempting to use the EDMA controller to send and receive data > via the McBSP which in turn interfaces to the AIC23EVM codec (which > sends and receives 32bit samples (16bits per left and right channel)). > > Currently, I can send and receive data to the McBSP using the polling > technique and this is working perfectly with no problems what so ever, > so I'm now ready to advance to the EDMA stage. To do this, I thought I > could make a few changes to the "audio" project example in the ccs > examples folder, but I haven't been that lucky. |
